Efficacy of injectable platelet-rich fibrin and microneedling for thin gingival phenotype: a systematic review and meta-analysis

Thin gingival phenotypes, characterized by a reduced gingival thickness (GT), are particularly susceptible to recession and inflammation. Injectable platelet-rich fibrin (i-PRF) and microneedling (MN) are emerging minimally invasive approaches for enhancing gingival thickness and improving periodontal health. To evaluate the efficacy of i-PRF and MN combination compared to i-PRF or MN monotherapy in the treatment of thin gingival phenotype. A comprehensive literature search was conducted across five databases with no language restrictions. Studies were selected based on predefined selection criteria that assessed primary outcomes (Gingival Thickness - GT, Width of Keratinised Tissue - KTW). Four split-mouth, prospective randomized trials involving 116 participants were included. Data from these studies were extracted individually by two reviewers, with a risk of bias assessment performed using the Cochrane RoB 2 tool. A meta-analysis was executed using RevMan Version 5.1. Of the 164 studies initially identified, four studies were eligible for inclusion and three for the meta-analysis. The combined use of i-PRF and MN showed a significant increase in GT, particularly within the first three months, compared to i-PRF alone. However, no significant differences were found for KTW across groups. The results for secondary outcomes, including clinical attachment level (CAL), probing depth (PD), and plaque index (PI) showed significant improvements, with i-PRF + MN leading to enhanced patient comfort and aesthetic satisfaction. The certainty evidence was estimated as low. i-PRF combined with MN may provide an adjunctive benefit for increasing GT in thin periodontal phenotypes, particularly within the first three months. These results should be interpreted with considerable caution given the small number of studies included and the high risk of bias. While a modest improvement in GT was observed with the combination approach, the impact on KTW remains inconclusive.